Sony TC366 loud crackling noise.

[philips KT3]

I have several of these machines all giving superb audio, but one is working on one channel only and both channels have loud crackling noise. I have cleaned the heads and used Servisol on the switches, record level controls, the rotary switches on the back of the speed control and at the rear of the main control knob. I am coming to the conclusion it may be a cap in one amplifier, but dreading the thought of dragging the amp out, also it's many years since I last worked down to component level, in TV sets not recorders.

Gerard

[philips KT3]

I have not tackled the crackling noise fault yet because I thought I would have by now received lots of advice from the many experts on the forum, but alas nobody has helped so far. One thing I have done is blown out all the dust and then it played quietly on two channels, albeit with the same loud crackles. So it could be a bad soldered joint or an earthing tag etc. So it looks like I am alone with this fault so I had better start dragging out the amplifiers.

Gerard.

[ms660]

Try wiggling the tops of the transistors in the affected channel(s).

Lawrence.

[sp10mk11]

Or you could try a slightly damp end of a finger across the pins, this often shows up a leaking transistor.

[philips KT3]

Thanks Lawrence and SP10. I will start to get underneath now but don' t know which amp is which. Have been looking on web for service data but cant see any. In my old TV service days I used to heat up or freeze microchips to check for faults but this is all transistor. Would that trick work on transistors? I should have mentioned that when I blew out the muck and dust the second channel only played for a few minutes.

Gerard

[philips KT3]

Hi Lawrence and SP10. I have made a recording on the faulty machine and played it back on a good one. The right hand channel is very good without crackles but when I press down the left switch the noise is deafening with just a hint of music. I have tried to pull out the two boards but looks a major job, removing the bars on the chassis etc. Don't know which board is for record or playback. I have just seen the comments on the old Decca Bradfords and couldnt resist adding a comment.

Gerard.

[Gulliver]

The service manual ought to be at hifiengine.com

What you describe does sound like a component failure in one of the amp circuits. I would follow the suggestion of tapping or wiggling transistors to see if it has any effect.

[philips KT3]

Thanks Gulliver will do that. Looks like I have to dismantle more chassis members to get at the components so may institute more faults than I already have but don't have much choice.

Gerard.

[philips KT3]

Since moving the amplifier boards out a little the machine is now erasing, recording and playing back on both channels but still with a loud noise on the left channel. Also when I switch on without any tape loaded up the noise is there mostly in the left channel. I haven't put any heat or cold on the transistors and caps yet as I can barely get near them, just a mass of cables covering the boards, I wish I could get to the boards as easily as I used to in my TV repair days.

[sp10mk11]

Tell me have you thoroughly cleaned the record/play switches on the circuit board?
Also yes a damp finger on the pins of a transistor can often show up if it has a dry joint (though not so common on old Sony machines), often the raucous crackling will stop for a while if you have located the correct transistor
Gary

[The Philpott]

Philips KT3,

What type are the signal connectors on the back of the Amp? Phono or something else?
(I don't know the age of the Sony TC366)

[The Philpott]

Oh i see it's a reel to reel recorder. Still, what are the connectors?

[julie_m]

Is there enough access for you to probe about with something long, thin and non-conductive like a chopstick or plastic knitting needle, in the hope of locating the faulty connection by deliberately disturbing it?

[philips KT3]

thanks guys.things have changed yet again.will get back to you all in an hour or so with details Gerard

[philips KT3]

The leads are RCA.yes I have poked around with stick.yes all switches cleaned with servisol.plays back tape recorded on good machine but only on one channel.if I plug in the second rca lead I hear the loud noise.If I turn on without any tape on machine the noise is there.unless I unplug one lead.Noise comes through headphone all the time.Records and plays back ok on one channel with one lead only but when I plug in the other lead that channel plays very faintly but with lots of noise.Gerard

[philips KT3]

Why Sony designed the amplifier boards like this I will never know.Just another couple of inches in depth in the cabinet could have made a much easier layout.If any of you clever guys have ever removed the boards please tell me how.There are two dozen or so thin leads going to each board with looms going across both.Its hard to even see the transistors let alone tap them.But there is no use moaning about the design now ,the point is I have to fix the machine.I never gave up with a tv fault and dont intend to give up here.Hmmm,brave words indeed,Gerard

[The Philpott]

Is RCA also known as Phono?
I once had an identical problem but with later SCART technology. Phono is more robust of course, but the socket boards can shift around during connection/disconnection if poorly designed.

Try the freeze spray method shown on youtube? It is certainly capable of showing up duff ceramic capacitors for example.

[philips KT3]

Hi philpot. my comp go crazy with windows ten. will try send

Yes same phono. all ok there. I used freezer and heat years ago on tv sets but imposs to get to components on the boards. have you ever seen them on a Sony. its a jungle of wires covering them Gerard

The fault could be simply a faulty cap across the mains input as the noise is there at switch on without any tape. Perhaps I am grasping at straws as they say.

[philips KT3]

How do I release the clamp on the power cable.Any ideas.Gerard

[AC/HL]

Originally Posted by The Philpott

Is RCA also known as Phono?

Phono is the popular name for the RCA connector these days, but as with many things it is the same but different. The central pin tends to be shorter, and of course, fancy finishes are de rigeur.